ground loop noise? its bad

[Race Car Driver]

So I finally called comcast and got the HDcable package.
With the new "cable box" connected im getting a quite loud hiss through my amps. I will try and be as brief to the point as I can.

Two bryston amps plugged into the wall for the mains

Monster power 3600 surge/filter with the following components plugged in
Denon CD
Denon LD
Denon DVD
Yamaha 5990 reciever
Aragon 4004 amp for center
PS2

Now I have been running this way for.... over a year now? No issues what so ever. Its been working great.

Added the comcast cable box, plugged in the optical and component cable into reciever, and power plug into the monster power surge. No noise, as SOON as i plug in the coax into the back of the comcast cable box, the amps start hissing really really bad. I then fed the coax into the monster, and from there into the cable box. That helped quite a bit, however the noise is still there and kind of annoying.

Clif notes, Coax cable from comcast, as soon as that is plugged into the box, I get buzzing noise from my amps.

Any suggestions?

[Kevin D]

Parts-express cable ground loop isolator. Like $10 and will solve your problem.

If you unplug the component video cable does it stop as well? I noticed you said 'new' cable box, I'm assuming you had an old digital only one (or straight to the TV). I've seen bad ground loops from cable only enter in when using the component inputs before. IE, something on the component side of things (TV, receiver, etc) lets the issue come about.

Kevin D.